An estimated 40,000 men and women worked

at Ground Zero, the former site of the World

Trade Center (WTC) in New York City, and

at the Staten Island landfill, the principal

wreckage depository in the days, weeks, and

months after 11 September 2001 (Levin et al.

2004). These workers and volunteers included

traditional first responders such as firefighters,

law enforcement officers, and paramedics, as

well as a diverse population of operating engineers, laborers, ironworkers, railway tunnel

cleaners, telecommunications workers, sanitation workers, and staff of the Office of the

Chief Medical Examiner. These men and

women carried out rescue-and-recovery operations, restored essential services, cleaned up

massive amounts of debris, and in a time

period far shorter than anticipated, deconstructed and removed remains of buildings.

Many had no training in response to civil disaster. The highly diverse nature of this workforce posed unprecedented challenges for

worker protection and medical follow-up.

Workers were exposed to a complex mix

of toxic chemicals and to extreme psychological trauma. These exposures varied over

time and by location (Landrigan et al. 2004;

Lioy et al. 2002). Combustion of 90,000 L of

jet fuel immediately after the attacks created a

dense plume of black smoke containing

volatile organic compounds (including benzene), metals, and polycyclic aromatic

hydrocarbons. The collapse of the twin towers (WTC 1 and WTC 2) and then of a

third building (WTC 7) produced an enormous dust cloud containing thousands of

tons of coarse and fine particulate matter

(PM), cement dust, glass fibers, asbestos,

lead, hydrochloric acid, polychlorinated

biphenyls (PCBs), organochlorine pesticides,

and polychlorinated dioxins and furans

(Clark et al. 2003; Landrigan et al. 2004;

Lioy et al. 2002; McGee et al. 2003). U.S.

Environmental Protection Agency (EPA) estimates of airborne dust ranged from 1,000 to

> 100,000 μg/m3 (U.S. EPA 2002). The high

content of pulverized cement made the dust

highly caustic (pH 10–11) (Landrigan et al.

2004; Lioy et al. 2002).

Dust and debris gradually settled, and rains

on 14 September further diminished the intensity of outdoor ambient dust exposure.

However, rubble-removal operations repeatedly reaerosolized the dust, leading to continuing intermittent exposure for many months.

Fires burned both above and below ground

until December 2001 (Banauch et al. 2003;

Chen and Thurston 2002; U.S. EPA 2003).

Air levels of certain contaminants remained

elevated well into 2002, with spikes in benzene

and asbestos levels occurring as late as March

and May 2002, respectively (U.S. EPA 2003).

Workers began noting symptoms soon

after September 11, most commonly involving

the aerodigestive tract (upper and lower respiratory tract and esophagus) (Banauch et al.

2006; Salzman et al. 2004; Szeinuk et al.

2003). New York City Fire Department

(FDNY) firefighters experienced persistent

cough, termed the “World Trade Center

Environmental Health Perspectives • VOLUME 114 | NUMBER 12 | December 2006 1853

Research

Address correspondence to R. Herbert, Department

of Community and Preventive Medicine, Mount

Sinai School of Medicine, One Gustave L. Levy Place,

Box 1057, New York, NY 10029 USA. Telephone:

(212) 241-5664. Fax: (212) 824-9015. E-mail:

robin.herbert@mssm.edu

We thank S. Carroll, S. Jiang, E. Jurgel, H. JumanJames, C. Katz, K. Kirkland, P. Landsbergis,

K. Leitson, B. Newman, N. Nguyen, R. Smith,

L. Stevenson, J. Weiner, other staff and patients of

the World Trade Center Worker and Volunteer

Medical Screening Program (MSP), and labor, community, and volunteer organizations for their contributions to this article and their involvement with the

MSP. We especially thank the American Red Cross

Liberty Fund, The September 11th Recovery

Program, The Bear Stearns Charitable Foundation,

The September 11th Fund, The Robin Hood

Foundation Relief Fund, and many others. 

This work was supported by the Centers for

Disease Control and Prevention and the National

Institute for Occupational Safety and Health, contract

200-2002-0038 and grant 5U1O 0H008232.

The authors declare they have no competing

financial interests.

Received 9 August 2006; accepted 5 September

2006.

The World Trade Center Disaster and the Health of Workers: Five-Year

Assessment of a Unique Medical Screening Program 

Robin Herbert,1 Jacqueline Moline,1 Gwen Skloot,2 Kristina Metzger,1 Sherry Baron,3 Benjamin Luft,4

Steven Markowitz,5 Iris Udasin,6 Denise Harrison,7 Diane Stein,1 Andrew Todd,1 Paul Enright,8

Jeanne Mager Stellman,1,9 Philip J. Landrigan,1 and Stephen M. Levin1

1Department of Community and Preventive Medicine, and 2Division of Pulmonary, Critical Care & Sleep Medicine, Mount Sinai School of

Medicine, New York, New York, USA; 3Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational

Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA; 4Department of Medicine, State University of New

York at Stony Brook, Port Jefferson, New York, USA; 5Center for Biology of Natural Systems, Queens College, Flushing, New York, USA; 6Environmental and Occupational Health Sciences Institute, University of Medicine & Dentistry of New Jersey, Piscataway, New Jersey,

USA; 7Department of Environmental Medicine, Bellevue Hospital Center/New York University School of Medicine, New York, New York,

USA; 8Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and

Prevention, Morgantown, West Virginia, USA; 9Mailman School of Public Health, Columbia University, New York, New York, USA

BACKGROUND: Approximately 40,000 rescue and recovery workers were exposed to caustic dust and

toxic pollutants following the 11 September 2001 attacks on the World Trade Center (WTC).

These workers included traditional first responders, such as firefighters and police, and a diverse

population of construction, utility, and public sector workers. 

METHODS: To characterize WTC-related health effects, the WTC Worker and Volunteer Medical

Screening Program was established. This multicenter clinical program provides free standardized

examinations to responders. Examinations include medical, mental health, and exposure assessment

questionnaires; physical examinations; spirometry; and chest X rays.

RESULTS: Of 9,442 responders examined between July 2002 and April 2004, 69% reported new or

worsened respiratory symptoms while performing WTC work. Symptoms persisted to the time of

examination in 59% of these workers. Among those who had been asymptomatic before

September 11, 61% developed respiratory symptoms while performing WTC work. Twenty-eight

percent had abnormal spirometry; forced vital capacity (FVC) was low in 21%; and obstruction was

present in 5%. Among nonsmokers, 27% had abnormal spirometry compared with 13% in the

general U.S. population. Prevalence of low FVC among nonsmokers was 5-fold greater than in the

U.S. population (20% vs. 4%). Respiratory symptoms and spirometry abnormalities were significantly associated with early arrival at the site.

CONCLUSION: WTC responders had exposure-related increases in respiratory symptoms and pulmonary function test abnormalities that persisted up to 2.5 years after the attacks. Long-term medical

monitoring is required to track persistence of these abnormalities and identify late effects, including

possible malignancies. Lessons learned should guide future responses to civil disasters.

KEY WORDS: air pollution, disaster response, occupational lung disease, pulmonary function,

September 11, spirometry, World Trade Center. Environ Health Perspect 114:1853–1858 (2006).

doi:10.1289/ehp.9592 available via http://dx.doi.org/ [Online 6 September 2006]
cough,” which was accompanied by respiratory

distress and bronchial hyperreactivity (Prezant

et al. 2002). A sample of FDNY firefighters

who had sustained extreme exposures on

September 11 was nearly 8 times more likely to

manifest bronchial hyperreactivity than firefighters with lower exposures when examined

after 6 months (Banauch et al. 2003). Laborers

and ironworkers manifested new-onset cough,

wheeze, and sputum production (Geyh et al.

2005; Skloot et al. 2004), likely attributable to

respiratory inflammation caused by the highly

alkaline dust (Chen and Thurston 2002). 

Other reported pulmonary effects included

cough, asthma, and reactive airway dysfunction

syndrome (Balmes 2006; Banauch et al. 2006).

Chronic rhinosinusitis, vocal cord inflammation, and laryngitis (de la Hoz et al. 2004) and

case reports of eosinophilic pneumonia (Rom

et al. 2002), granulomatous pneumonia, and

bronchiolitis obliterans (Mann et al. 2005;

Safirstein et al. 2003) were also reported. 

Although New York has an extensive hospital network and strong public health system,

no existing infrastructure was sufficient for

providing unified and appropriate occupational health screening and treatment in the

aftermath of September 11. Local labor

unions, who made up the majority of responders, became increasingly aware that their

members were developing respiratory and psychological problems; they initiated a campaign

to educate local elected officials about the

importance of establishing an occupational

health screening program. In early 2002,

Congress directed the Centers for Disease

Control and Prevention (CDC) to fund most

of the WTC Worker and Volunteer Medical

Screening Program (MSP), an action largely

attributable to the collaborative efforts of organized labor and elected officials. The goals of

the program were as follows: 

• To rapidly build a regional and national

consortium of occupational medicine clinics

to conduct geographically convenient standardized medical evaluations

• To identify WTC responders, notify them

about this program, and encourage participation

• To provide clinical examinations for eligible

individuals to identify WTC-related physical

and/or mental health conditions

• To coordinate referral for follow-up clinical

care for affected individuals

• To educate workers and volunteers about

exposures and associated risks to their health

• To advise affected individuals about available

benefit and entitlement programs

• To establish “baseline” clinical status for individuals exposed at or near Ground Zero for

comparison with future clinical assessments.

In April 2002, the Irving J. Selikoff

Center for Occupational and Environmental

Medicine (COEM) at Mount Sinai was

awarded a contract by the National Institute

for Occupational Safety and Health (NIOSH)

to establish and coordinate the MSP. The

Bellevue/New York University Occupational

and Environmental Medicine Clinic, the

State University of New York Stony Brook/

Long Island Occupational and Environmental

Health Center, the Center for the Biology of

Natural Systems at Queens College in New

York, and the Clinical Center of the

Environmental & Occupational Health

Sciences Institute at UMDNJ-Robert Wood

Johnson Medical School in New Jersey were

designated as the other members of the

regional consortium. The Association of

Occupational and Environmental Clinics was

designated to coordinate a national examination program for responders who did not live

in the New York/New Jersey area. 

In this article we describe the design and

implementation of the MSP and the prevalence of selected clinical findings from screening examinations conducted between July

2002 and April 2004 in those from whom

informed consent and HIPAA (Health

Insurance Portability and Accountability Act

1996) authorization were obtained. Mental

health service provision and findings will be

presented in a separate paper. 

Materials and Methods

Establishing the cohort: identification and outreach. The target population was approximately 18,000 WTC responders not eligible to

participate in other federally funded programs

(e.g., FDNY, federal workers, New York State

workers). Because responders came from many

sectors, a high proportion as unpaid volunteers, no systematic roster of names and contact information was available. An MSP

outreach unit was therefore established and

staffed by people experienced in occupational

health and familiar with key organizations, primarily labor unions representing responders. 

The MSP executive steering committee. To

ensure key stakeholder input into all aspects of

program development and oversight, an executive steering committee (ESC) was established; the ESC included representatives from

each of the consortium clinics, representatives

from labor unions, employers, and technical

experts from relevant fields. 

The ESC advised the program directors

on all program decisions and on basic components of the medical examination, eligibility

criteria, and the outreach plan. An advisory

council of > 100 people was created several

months after the start of the program to

broaden stakeholder involvement and to tap

into the enthusiasm and creativity of responder

organizations. Generally 40–50 responder representatives attended quarterly advisory council

meetings. The ESC and advisory council

helped maintain open lines of communication

with representatives of the program’s diverse

responder population. 

Examination eligibility. To be eligible to

receive an examination, a responder must have

fallen into one of two categories: For the first

category, the responder must have been a rescue, recovery, debris-cleanup and related support services worker, or volunteer in a) lower

Manhattan (south of Canal St.), b) the Staten

Island Landfill, and/or c) the barge loading

piers, and must have worked and/or volunteered on-site for 4 hr on 11–14 September

2001, for at least 24 hr during the month of

September, or for at least 80 hr during the

months of September, October, November,

and December combined.

To fall into the second category, the

responder must have been an employee of the

Office of the Chief Medical Examiner

(OCME), involved in the examination and

processing of human remains, or other

morgue worker who performed similar postSeptember 11 functions for OCME staff; a

worker in the Port Authority Trans-Hudson

Corporation tunnel through 1 July 2002 for a

minimum of 24 hr; or a vehicle-maintenance

worker with post-September 11 functions

within the requisite timeframes and exposed

to WTC debris while retrieving, driving,

cleaning, repairing, and maintaining contaminated vehicles.

Development of the examination protocol.

The clinical consortium partners, supplemented by experts in psychiatry, pulmonary

medicine, otolaryngology, industrial hygiene,

and epidemiology, collaborated in protocol

development to provide high quality standardized occupational health screening examinations and gather information for a research

database to enable scientific assessment of the

full health impact of the disaster. Early in

protocol planning it was decided that direct

clinical services had priority where clinical

protocols conflicted with collection of

research data.

Standardized medical examination.

Responders received a clinical screening

evaluation consisting of medical, mental

health, and exposure-assessment questionnaires; a standardized physical examination;

and pre- and postbronchodilator spirometry,

complete blood count, blood chemistries, urinalysis, and chest radiograph. Participants

received both immediate and final letters with

examination results and a face-to-face physician consultation at the end of the examination day. Participants were provided referrals

for evaluation and treatment for physical or

mental health conditions identified in the

screening examination.

A trained health care practitioner administered a medical questionnaire on selected diagnoses and prior upper and lower respiratory

conditions (e.g., chronic sinusitis and asthma),

Herbert et al.

1854 VOLUME 114 | NUMBER 12 | December 2006 • Environmental Health Perspectives
occurrence of symptoms in the year before

11 September 2001, during the period the

subject worked at the WTC site, for the

month before the screening examination, and

whether preexisting symptoms and diagnoses

worsened during their WTC work. A questionnaire also asked about smoking history.

Where possible, questions were adapted from

standardized instruments (e.g., Burney et al.

1989; European Community Respiratory

Health Survey 1994; Miller et al. 2005;

National Center for Health Statistics 1996;

NIOSH 2006; Piccirillo et al. 2002). 

We used an interviewer-administered survey instrument to obtain pre- and postSeptember 11 occupational and environmental

exposure histories, including dates that responders reported for first working or volunteering

for September 11–related duties and, for those

present on September 11, whether they were

exposed to the cloud of dust from the building

collapses. We constructed the ordinal daterelated categories shown in the tables as a

rough measure of relative dust exposures, and

also categorized workers by location where they

spent the majority of their time when first

working at Ground Zero. We also obtained

data on respirator type and use during the first

week of the WTC recovery; those data will be

reported in subsequent analyses.

Eligible responders were invited for clinical

examinations irrespective of their willingness to

provide consent to have data aggregated. Only

data from responders providing institutional

review board consent and HIPAA authorization (on or after 14 April 2003) are included

in data analyses.

Spirometry. Spirometric examination

employed the EasyOne spirometer (ndd

Medical Technologies, Chelmsford, MA)

using standard techniques (Miller et al. 2005).

We compared spirometry results to age-, sex-,

and ethnic-specific reference values derived

from the third phase of the National Health

and Nutrition Examination Survey (NHANES

III) (Hankinson et al. 1999). Interpretation

followed the recently combined American

Thoracic Society and European Respiratory

Society guidelines (Pellegrino et al. 2005).

Only spirometry of acceptable quality, as

defined by international guidelines (Miller

et al. 2005), was included in the analysis

(n = 8,384). Airway obstruction was defined as

forced expiratory volume/forced vital capacity

(FEV1/FVC) below the lower limit of normal

(LLN) with a normal FVC. Spirometry with

FVC < LLN but FEV1/FVC ≥ LLN was categorized as “low FVC.” Obstruction and low

FVC was defined as FEV1/FVC < LLN and

FVC < LLN. A significant bronchodilator

response was defined as an increase in FEV1 or

FVC of < 12% and 200 mL. Comprehensive

spirometry quality assurance was an integral

aspect of this program. 

Data analysis. We used SAS software (version 9.1; SAS Institute, Inc., Cary, NC) for all

analyses. Categorization of occupational sector

was based on the union and/or organization to

which the responder reported belonging during work on the WTC effort. We categorized

prevalence of specific health outcomes by date

of arrival and exposure to the dust cloud and

used the Cochrane-Armitage trend test to

assess significance of trends in prevalence

across exposure categories.

Results

The MSP began examining responders in July

2002, 3 months after receipt of federal funding. Of the 16,528 responders meeting eligibility criteria, we examined 11,095 responders

in the New York/New Jersey regional clinical

consortium and 645 elsewhere between

16 July 2002 and 16 April 2004. In the New

York/New Jersey consortium, 9,442 of these

responders provided appropriate consent to

be included in this report. 

Demographics. The responders screened in

this program were predominantly male (87%)

and white (66%), with a median age of

42 years (range, 18–82 years) (Table 1). More

than 92% lived in the tristate (New York, New

Jersey, Connecticut) area, 54% from New

York City and 15% on Long Island; 86% were

union members; 34% were construction workers; and 29% worked in law enforcement. We

conducted > 14% of the examinations in languages other than English.

Time of arrival and location. Of the

> 40% of the responders who first arrived for

work at the site on September 11, 49%

reported having been engulfed in the building-collapse dust cloud (Table 1). Another

30% first arrived on 12 or 13 September.

Irrespective of date of arrival, 35% of responders began working on the pile or in the pit at

Ground Zero; another 55% worked adjacent

to the pile; and the remaining 10% worked at

other sites. The reported average duration of

exposure (the time between the first and last

days of work on the WTC effort) was 171 days

(range, 1 day to ≥ 2.5 years). The average time

between first work day and the MSP examination was 20 months.

Symptoms. Most of the 9,442 responders

examined reported being asymptomatic in the

year prior to September 11 for lower respiratory tract symptoms (85%), and a large majority (66%) were asymptomatic for upper

respiratory tract symptoms (Table 2). In the

previously asymptomatic group, 44% reported

developing lower respiratory symptoms and

55% developed upper respiratory symptoms

while engaged in WTC-related work. These

new symptoms were persistent in many; at the

time of exam, 32% reported current lower respiratory symptoms and 44% reported current

upper respiratory symptoms (Table 2). Fully

69% of all responders reported having had at

least one worsened or newly incident respiratory symptom while performing WTC

response work (63% upper airway and 47%

lower airway symptoms, with overlap between

the groups) (Table 3). Respiratory symptoms

persisted to the time of examination in 59%

of the population.

Early arrival at the WTC site was significantly associated with an increased reported

prevalence of both newly incident and worsened respiratory symptoms (Table 3). We

observed the highest prevalence among those

who arrived on September 11 and were

exposed to the dust cloud (54% lower respiratory and 66% upper respiratory symptoms).

Those who began work on September 11 but

who were not directly exposed to the dust

cloud had the next highest prevalence (47%

lower respiratory and 62% upper respiratory

The WTC disaster and the health of workers: 5-year assessment

Environmental Health Perspectives • VOLUME 114 | NUMBER 12 | December 2006 1855

Table 1. Demographic and exposure characteristics of the WTC MSP study population (n = 9,442).

No. (%)

Sex

Male 8,186 (86.7)

Female 1,256 (13.3)

Race

White 6,203 (65.7)

Black 1,060 (11.2)

Asian 121 (1.3)

Other 253 (2.7)

Unknown 1,805 (19.1)

Hispanic ethnicity

Yes 2,249 (23.8)

Language of exam

English 8,114 (85.9)

Spanish 984 (10.4)

Polish 311 (3.3)

Other 33 (0.3)

Union member

Yes 8,075 (86.0)

Union/organization affiliation

Construction 3,209 (34.0)

Law enforcement 2,776 (29.4)

Public sector (blue collar) 739 (7.8)

Technical and utilities 683 (7.2)

Transportation 516 (5.5)

Cleaning/maintenance 258 (2.7)

Volunteers 245 (2.6)

Firefightersa 138 (1.5)

Health care 83 (0.9)

News agencies 81 (0.9)

Office/administration/professional 50 (0.5)

Other 664 (7.0)

Time first began WTC-related work

11 September 2001 3,812 (40.5)

In dust cloud 1,878 (20.0)

Not in dust cloud 1,934 (20.5)

12–13 September 2001 2,801 (29.8)

14–30 September 2001 2,133 (22.7)

On or after 1 October 2001 666 (7.1)

Location of majority of work

On the pile/in the pit 3,215 (34.8)

Adjacent to pile/pit 5,074 (54.8)

Landfill 313 (3.4)

Barges/loading pier 106 (1.1)

OCME 77 (0.8)

Elsewhere south of Canal St. 466 (5.0)

aDoes not include active-duty New York City firefighters.
symptoms). We found a continuing statistically significant downward trend (although the

prevalence remained high) in the incidence of

reported symptoms for later arrival dates. Even

those responders who arrived at the site on or

after 1 October had a 41% prevalence of lower

respiratory and a 59% prevalence of upper respiratory symptoms, nearly three times the percentage who had reported lower respiratory

symptoms in the year prior to September 11,

and nearly twice of the percentage who

reported prior upper respiratory symptoms.

Of the 8,384 participants with acceptable

quality pulmonary function exams, 28% had

abnormal prebronchodilator spirometry

results (Table 4). A low FVC was the most

common abnormality (21%), whereas

obstruction occurred in 5% and a mixed pattern (obstruction and low FVC) in 2%. We

also documented a significant response to

bronchodilator in 910 (11%) of participants

including 33% of those with obstruction,

56% with a mixed pattern, and 18% of those

with a low FVC. 

Compared with a U.S. general population

sample of employed, adult, white males

(Mannino et al. 2003), the 4,641 participants

who had never smoked had a higher prevalence of abnormalities on spirometry (27% vs.

13%). The difference was mainly attributable

to a higher prevalence of tests with a low FVC

(20% vs. 4%). 

We observed a statistically significant

association between time of arrival and low

FVC, with a higher prevalence of abnormality

in those who arrived earlier (Table 5). There

was no significant difference in the prevalence

of obstruction based on onset of exposure.

Thirty-one percent of the sample reported

having received medical care for WTC-related

respiratory conditions. A total of 17% of

examinees reported missing work because of

WTC-related health problems. Of the 1,973

workers with a self-reported diagnosis of

sinusitis, 40% were seen by a doctor for this

condition during the 6 months after

September 11, compared to only 13% in the

6 months before September 11. Similar

increases were reported in the numbers of

responders who sought medical help for acute

bronchitis (45% vs. 18%) and pneumonia

(10% vs. 1%).

Discussion

Two principal lessons emerge from our experiences with the WTC MSP. First, the prevalence rates of respiratory and other symptoms,

and the prevalence of pulmonary function

abnormalities in the nearly 10,000 WTC

workers and volunteers whom we examined

clinically between 2002 and 2004 were very

high, and they are persistent. Health effects

were most frequent in responders who sustained the most intense exposures. In the aftermath of future civil disasters, hospitals and

health care providers will need to anticipate

and prepare for the severe health consequences

that inevitably result from the extreme exposures sustained by workers in these situations. 

Second, in the event of future disasters, it

is likely that existing health care facilities and

public health programs will not be sufficiently

robust or flexible to deal with the special

needs and complex health problems sustained

by responders and victims. It will likely be

necessary to establish large, multicenter medical follow-up programs such as were needed

in New York. The more rapidly such programs can be established and funded, the

more quickly essential services will be provided (Rosner and Markowitz 2006).

Abnormal spirometry was still evident in

almost one-third of all WTC workers and

volunteers 1–2.5 years after 11 September

2001. The most common spirometric abnormality seen was a low FVC, which had also

been found in the first 1,138 participants

from this group (Levin et al. 2004). Low

FVC was about 5 times more prevalent

among nonsmokers than expected in the general U.S. population, based on NHANES III

data (Mannino et al. 2003). Prevalence of low

Herbert et al.

1856 VOLUME 114 | NUMBER 12 | December 2006 • Environmental Health Perspectives

Table 3. Prevalence of new or worsened respiratory symptoms among WTC workers by date of arrival for work at WTC site and by exposure to the dust cloud

(n = 9,442).

Arrived on 11 September Arrived Arrived Arrived on or

All responders In dust cloud Not in dust cloud 12–13 September 14–30 September after 1 October

(n = 9,442) (n = 1,878) (n = 1,934) (n = 2,801) (n = 2,133) (n= 666) Trend test

[no. (%)] [no. (%)] [no. (%)] [no. (%)] [no. (%)] [no. (%)] p-valuea

Lower respiratory symptoms

Dry cough 2,688 (28.7) 640 (34.2) 587 (30.6) 777 (28.0) 538 (25.5) 140 (21.3) < 0.001

Cough with phlegm 1,320 (14.1) 328 (17.6) 256 (13.4) 373 (13.5) 275 (13.0) 84 (12.7) < 0.001

Shortness of breath 1,613 (17.3) 390 (20.9) 298 (15.6) 471 (17.1) 339 (16.1) 109 (16.6) 0.001

Wheeze 1,408 (15.1) 339 (18.3) 296 (15.5) 403 (14.6) 281 (13.4) 85 (13.0) < 0.001

Chest tightness 1,393 (15.4) 334 (18.5) 268 (14.4) 384 (14.3) 311 (15.2) 91 (14.1) 0.003

Any lower respiratory symptom 4,371 (46.5) 1,017 (54.2) 912 (47.2) 1,232 (44.2) 930 (43.8) 271 (40.8) < 0.001

Upper respiratory symptoms

Sinus-relatedb 510 (37.3) 785 (41.9) 712 (36.9) 1,020 (36.6) 783 (37.0) 200 (30.1) < 0.001

Nasal-relatedc 4,552 (48.4) 982 (52.4) 939 (48.6) 1,334 (47.9) 981 (46.3) 300 (45.1) < 0.001

Throat-relatedd 4,128 (43.9) 885 (47.2) 847 (43.9) 1,199 (43.1) 923 (43.6) 264 (39.7) 0.001

Any upper respiratory symptom 5,883 (62.5) 1,233 (65.8) 1,205 (62.4) 1,719 (61.7) 1,316 (62.1) 394 (59.2) 0.001

Any respiratory symptom 6,479 (68.8) 1,376 (73.4) 1,345 (69.7) 1,878 (67.3) 1,435 (67.7) 429 (64.5) < 0.001

aOne-sided p-values using the Cochran-Armitage trend test. bFacial pain or pressure, head or sinus congestion, or postnasal discharge. cBlowing your nose more than usual, stuffy

nose, sneezing, runny nose, or irritation in nose. dThroat irritation, hoarseness, sore throat, or losing your voice (laryngitis).

Table 2. Prevalence of lower and upper respiratory symptoms among the WTC MSP study population

(n = 9,442).

Did not report symptoms in year before September 11

Reported symptoms in year New symptoms while Symptoms still present 

before September 11 working at WTC site in month before exam

[no. (%)] [no. (%)] [no. (%)]

Lower respiratory symptoms

Dry cough 362 (3.9) 2,541 (28.3) 1,534 (17.1)

Cough with phlegm 325 (3.5) 1,183 (13.1) 742 (8.2)

Shortness of breath 344 (3.7) 1,477 (16.5) 1,266 (14.1)

Wheeze 557 (6.0) 1,232 (14.1) 749 (8.6)

Chest tightness 464 (5.1) 1,258 (14.6) 933 (10.8)

Any lower respiratory symptom 1,451 (15.4) 3,486 (43.8) 2,535 (31.9)

Upper respiratory symptoms

Sinus-relateda 2,169 (23.1) 2,219 (30.7) 1,863 (25.8)

Nasal-relatedb 1,967 (20.9) 3,254 (43.8) 2,536 (34.1)

Throat-relatedc 887 (9.4) 3,579 (42.0) 2,450 (28.8)

Any upper respiratory symptom 3,148 (33.5) 3,453 (55.2) 2,772 (44.3)

Any respiratory symptom 3,767 (40.0) 3,443 (61.0) 2,846 (50.4)

aFacial pain or pressure, head or sinus congestion, or postnasal discharge. bBlowing your nose more than usual, stuffy

nose, sneezing, runny nose, or irritation in nose. cThroat irritation, hoarseness, sore throat, or losing your voice (laryngitis).
The WTC disaster and the health of workers: 5-year assessment

Environmental Health Perspectives • VOLUME 114 | NUMBER 12 | December 2006 1857

FVC was higher in responders who arrived at

the disaster site closer to the time of the collapse of the twin towers than in those who

arrived on or after 1 October.

There are several possible explanations for

the high rates of low FVC observed in this

group: a) true restriction due to parenchymal

lung disease (e.g., interstitial lung diseases such

as sarcoidosis, idiopathic pulmonary fibrosis,

pneumoconiosis); b) true restriction due to

physical factors such as obesity or chest wall

abnormalities; c) “pseudorestriction” due to air

trapping (e.g., airways obstruction) or submaximal inspiratory and/or expiratory effort

(typically the result of chest pain/tightness or

in an attempt to reduce coughing during the

test); or d) our selection of the reference value

used to define the lower limit of the normal

range for FVC. 

It is likely that, in some responders, the

observed increase in low FVC is due to air

trapping in the lungs, possibly due to inhalation of caustic dust and airborne pollutants in

the course of their WTC work. A finding that

supports this explanation is our observation of

an increase in FVC after administration of a

bronchodilator, seen in 18% of WTC workers

and volunteers with this pattern. 

Another possible explanation for our

observed abnormalities in pulmonary function

is our choice for the lower reference limit of

the normal range for FVC. In our analysis we

chose to use the Hankinson pulmonary reference values derived from NHANES III

(Hankinson et al. 1999), because we considered them to be most appropriate for an ethnically diverse population such as this workforce.

In previous studies of workers, several spirometry reference equations other than those from

NHANES III have been used (Crapo et al.

1981; Knudson et al. 1983; Miller et al. 1983;

Morris et al. 1973). Although the mean predicted values calculated from these five studies

are very similar for whites, differences in the

lower limits of the normal range provide large

differences in spirometry abnormality rates

when testing large, ethnically diverse groups of

workers. For example, when using the equations from Crapo et al. (1981), substantially

higher rates of obstruction but lower rates of

spirometric restriction (low FVC) were found

in whites in our cohort. It is also possible that

some responders have developed true restrictive

lung disease due to their WTC-related exposures. We anticipate that these issues will

become clearer with continuing prospective

follow-up of this cohort.

The MSP faced many challenges, and similar challenges are likely to arise in future

major civil disasters. We faced organizational

challenges in coordinating work at five clinical

sites in the New York/New Jersey metropolitan area, as well as in the national program.

There was no systematic roster of responders.

We found that a broad and vigorous outreach

program to systematically identify responders

and persuade them of the importance of

undergoing examination was essential. Most

of these workers, many of whom had volunteered their services after September 11, were

unable to take paid time off to be screened,

and many were not in the position to forfeit a

day’s wages. We needed to schedule the examinations at times and in locations that

respected those difficulties. The examination

content needed to be relevant and acceptable

to the responders and at the same time sufficiently standardized to permit interpretation

of aggregated clinical data. Translation was

one of the more challenging aspects of program coordination. More than 14% of

responders required non-English examinations

and written materials. 

The need for follow-up medical treatment

and for provision of social benefits in the

event of future civil disasters must be anticipated, and federal funds must be provided

early on to support such programs. There was

substantial social and economic disruption to

the lives of many of the responders, and benefits counseling became an urgent need and an

integrated component of the MSP. Many

responders needed follow-up treatment for

physical or mental health illnesses, and many

lacked health insurance. We were obliged to

secure private funding from philanthropic

organizations to develop and implement

treatment programs for responders. Federal

funding for treatment of these workers is

anticipated to begin in fall 2006.

Several limitations in these data should be

noted. We do not have pre-September 11 clinical information on our cohort. It may be that

responders who were sicker were more likely to

participate, leading to an overestimation of

risk. Conversely, we may be underestimating

risk because most responders were likely to

have been fit workers (healthy worker effect).

In this article we do not consider the psychological consequences, which we already know

to be serious (Smith et al. 2004). Subsequent

papers will address responder mental health. 

Conclusions

The workers and volunteers who served New

York City and the nation through their heroic

service in the aftermath of September 11 need

continuing medical surveillance and followup, especially because some diseases, such as

cancer, are of long latency. Malignant

mesothelioma resulting from exposure to

asbestos, for example, may not become evident for 30–50 years. These biological facts

plus the magnitude and complexity of the

exposures indicate that WTC responders

should be monitored for at least 20–30 years,

Table 4. Spirometry results (prebronchodilator) among the WTC MSP study population (n = 8,384).a

National populationb WTC MSP population

Never smoker Never smoker Former smoker Current smoker All

(%) [no. (%)] [no. (%)] [no. (%)] [no. (%)]

Normal 87.1 3,396 (73.2) 1,541 (72.8) 1,047 (67.1) 6,031 (71.9)

Obstructionc 8.0 237 (5.1) 97 (4.6) 114 (7.3) 451 (5.4)

Low FVCd 4.4 940 (20.3) 431 (20.3) 336 (21.5) 1,721 (20.5)

Obstruction and low FVCe 0.6 68 (1.5) 49 (2.3) 63 (4.0) 181 (2.2)

Total NA 4,641 (55.4) 2,118 (25.3) 1,560 (18.6) 8,384 (100.0)

NA, not applicable.

aOnly acceptable quality spirometric examinations are included, as described by Miller et al. (2005). bGeneral U.S. population sample of employed, adult, white males 17–69 years of age who never smoked (Mannino et al. 2003; NHANES III).

cFEV1/FVC ratio less than 5th percentile of predicted value and normal FVC. dFVC less than 5th percentile of predicted value

and a normal FEV1/FVC ratio. eFEV1/FVC ratio less than 5th percentile of predicted value and FVC less than 5th percentile of

predicted value.

Table 5. Spirometry results (prebronchodilator) by date of arrival for work at WTC site and exposure to the dust cloud among the WTC MSP study population

(n = 8,384).a

Arrived on 11 September Arrived Arrived Arrived on or

In dust cloud Not in dust cloud 12–13 September 14–30 September after 1 October Trend test

[no. (%)] [no. (%)] [no. (%)] [no. (%)] [no. (%)] p-valueb

Normal 1,160 (68.5) 1,222 (69.9) 1,781 (71.6) 1,397 (75.3) 453 (78.6) —

Obstructivec 81 (4.8) 96 (5.5) 140 (5.6) 104 (5.6) 28 (4.9) 0.418

Low FVCd 408 (24.1) 400 (22.9) 506 (20.3) 318 (17.1) 84 (14.6) < 0.001

Obstruction and low FVCe 44 (2.6) 29 (1.7) 61 (2.5) 36 (1.9) 11 (1.9) 0.095

aOnly acceptable quality spirometric examinations are included, as described by Miller et al. (2005). bOne-sided p-values using the Cochran-Armitage trend test. cFEV1/FVC ratio less

than 5th percentile of predicted value and normal FVC. dFVC less than 5th percentile of predicted value and a normal FEV1/FVC ratio. eFEV1/FVC ratio less than 5th percentile of predicted

value and FVC less than 5th percentile of predicted value.
Herbert et al.

1858 VOLUME 114 | NUMBER 12 | December 2006 • Environmental Health Perspectives

so that long-term effects are detected early,

when treatment would be most beneficial. 

Federal leadership is needed to bring

together a wide range of civilian and military

experts to prepare for the complex physical and

mental health issues and the environmental

issues certain to arise in future disasters. Future

disaster response must incorporate rapid

establishment of both diagnostic and treatment programs, and state and federal leadership must make a firm commitment for the

long-term follow up of exposed workers.

Finally, there is a need to ensure strong and

active participation by worker representatives

and local citizens. Their local knowledge is

unique, and it will not become available to

state and federal planners unless these vital

stakeholders are invited to take an active role

in the planning and implementation of

responses to future disasters. 

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